Interval Timer

What this tool does

Interval Timer runs a HIIT-style workout structure, alternating work and rest periods for a chosen number of rounds, with a visible countdown, colour-coded phase, sound cues at every transition, and a total-workout-time estimate.

Interval training, alternating focused bursts of work with short rest periods for a set number of rounds, is the structure behind HIIT and Tabata-style workouts, but tracking rounds and timing manually mid-workout is distracting at best.

This timer handles that structure automatically: set your work duration, rest duration and number of rounds, then let it run, with a colour-coded phase, countdown, and sound cue at every transition so you can focus entirely on the workout.

How to use Interval Timer

1. Set your work duration, rest duration and number of rounds.
2. Press Start.
3. Follow the colour-coded phase and countdown through each round.
4. A final sound and "Done!" message signal the workout’s end.

Tips for better results

• Tabata is a well-known specific interval pattern: 20 seconds work, 10 seconds rest, for 8 rounds, a widely used preset if you want a quick, intense structure.
• 30 seconds work / 15 seconds rest is a more moderate, general-fitness interval pattern, a reasonable starting point if Tabata’s intensity feels too aggressive.
• The total workout time estimate (work + rest, multiplied by rounds) helps you fit the session into an available time slot before starting.
• Keep the tab open and unmuted to hear the transition sound cues clearly over any workout noise or music.

Common use cases

• Running a HIIT or Tabata-style interval workout without a dedicated fitness app.
• Timing alternating work/rest intervals for any activity, not just exercise, cooking steps, study sprints, anything with a repeatable work/rest rhythm.
• Structuring a quick, time-boxed workout that fits a specific available time slot.
• Practicing a consistent interval training routine with hands-free timing.

Common mistakes to avoid

• Setting an unrealistic number of rounds or work duration for your actual fitness level, start conservative and increase intensity gradually across sessions rather than overestimating from the first attempt.
• Missing the Tabata preset’s specific intensity (20s work, 10s rest is genuinely demanding) and being caught off guard partway through if you expected something more moderate.
• Working out somewhere too noisy to hear the transition sound cues clearly, check your volume with a quick test before starting a session that depends on hearing the phase change.